The AMTB battery at Ebey's Landing consisted of two M1 90mm guns mounted on fixed M3 gun mounts and two M1 90mm guns mounted on M1A1 mobile carriages. The round concrete pads for the two fixed guns were laid 120' apart. The battery had a dual mission of defense against fast enemy motor torpedo boats and enemy aircraft. The effective range of the guns was about 8,000 yards. Each weapon required a crew of 15, 9 men in the gun squad and 6 men in the ammunition squad.

From FM 4-91:
"This weapon consists of the 90-mm gun M1 and top carriage M1A1 on the 90-mm gun mount M3. The mount M3 is of the turret type, the shielding being constructed of boiler plates. This boiler plate shield provide fragmentation protection only. No shielding is provided at the rear due to the requirements for service of the piece. A sighting port in the shielding in front permits sighting in direction by the gun pointer."